In recent years, nitride-based HEMT (high electron mobility transistor) has been applied in fields such as mobile, satellite, and radar communication. Among mainstream substrates a sapphire, a silicon, a silicon carbide, etc.) used for nitride material deposition, the cost of a silicon carbide substrate is generally more than 10 times as much as that of other types of substrates due to higher manufacturing cost of silicon carbide and limited supply thereof on the market. Although the silicon carbide substrates have higher cost, currently major high-performance HEMT devices require the use of silicon carbide substrates, which cannot be replaced by other substrates due to the high performance requirement of the HEMT device. Therefore, recovery of the silicon carbide substrate after testing or after failure of deposition of the nitride material has significant economic benefit.
Recycling the silicon carbide substrate that can be reused for HEMT epitaxy is very technically challenging because the recovered silicon carbide substrate requires not only a smooth surface but also no trace chemical contamination of the substrate surface. Currently conventional silicon carbide recycling technologies involve mechanical thinning and polishing, chemical contamination can be easily introduced due to the use of various polishing agents and polishing fluids. In addition, since a conventional recycling method uses a grinding and polishing process, the thickness of the silicon carbide substrate is reduced, and the reduction of substrate thickness can cause subsequent changes of nitride epitaxial process (such as the temperature of substrate surface during epitaxy), thereby affecting the performance of final devices.